The US is facing an unprecedented opioid epidemic. Methadone treatment is effective in reducing illicit opioid use and overdose death, yet waiting lists for Opioid Treatment Programs (OTPs) persist in numerous states. Federal regulations since 1993 permit the provision of interim methadone (IM) treatment ? consisting of supervised methadone administration without routine counseling ? for up to 120 days for people on OTP waiting lists. IM is on federal Substance Abuse and Mental Health Services Administration?s National Registry of Evidence-based Programs and Practices. Two randomized trials, including one conducted by our team, have shown that IM treatment is more effective than waiting list in increasing OTP admission and reducing illicit opioid use. Our team led the successful implementation and evaluation of IM in six Baltimore OTPs for 1,000 patients over an 18-month period. The Center for Substance Abuse Treatment recently commissioned the PI to author a white paper on IM that found barriers to the implementation of IM include lack of awareness and misconceptions about IM among some State Opioid Treatment Authorities (SOTAs) who must recommend its approval and OTP Directors who must implement it. Despite the ongoing opioid epidemic, IM?s effectiveness, and the persistence of OTP waiting lists, IM has rarely been used outside of research. Research is needed to find an effective approach to spur IM?s implementation. This application proposes a Type 3 implementation effectiveness study using a stepped-wedge randomized trial design in the context of Proctor?s implementation model. This study will adapt, deploy, and assess the effectiveness of an Implementation Facilitation strategy to spur the use of IM treatment. In this strategy, the PI will serve as the external facilitator to work with the National Association of State Alcohol and Drug Abuse Directors to co-lead a learning collaborative for participating SOTAs and OTP leadership of nine participating OTPs with waiting lists. Local OTP champions will be recruited and the PI will provide academic detailing, IM procedures training, and performance feedback to OTP staff. The IM operations manual from the team?s previous work will be used to train OTP staff. The Implementation Facilitation intervention will occur in 9 OTPs, and will include data collection for an estimated 6,120 adults on OTP waiting lists and 1,710 IM treatment admissions. The primary implementation outcome (Accessibility to methadone treatment), as well as secondary implementation (Uptake, Efficiency, Fidelity, Sustainability, Feasibility, and Acceptability) and clinical effectiveness (urine opioid testing results) outcomes will be measured using a combination of de-identified OTP data and qualitative SOTA and OTP staff semi- structured interviews. The proposed study is highly significant because it could demonstrate an effective approach to spur the implementation of IM treatment to reduce OTP waiting lists. This study is innovative in applying Implementation Facilitation, an approach used in mental health and primary care, to spur a significant change in how OTPs address the gap between treatment demand and capacity.